Ever since various hurricanes such as Camille in New Orleans, La., Andrew in Dade County, Fla. and Hugo in Charleston, S.C. have impacted the coastal cities in North America, replacement of existing and new tempered glass with high impact laminated windows have been the focus of various state and government agencies.
The degree and type of damage in these various cities were the subject of intensive studies to determine how the damage from high winds to buildings, both commercial and residential can be minimized. In addition to other recommendations, replacement of conventional float glass and insulated glass should be with high impact laminated windows. Prevailing opinions were that if the high winds could be kept out of the interior of the building, less damage to the structure should occur. Support for these opinions came from Hurricane Hugo which hit Charleston, S.C. in July, 1997.
Almost all of the tempered glass structures in high rise buildings failed while considerable less failure occurred with conventional laminated glass structures. Although the theory is controversial, the Florida State Building Code Agency in Dade County has instituted new and stringent requirements for high impact windows, both new and existing structures.
Insurance Companies have been the driving force for these requirements. Resistance to these changes have come from the construction industry and owners of high rise buildings who feel that these changes are too costly and will negatively impact new construction in Florida and other coastal areas in the United States.
However, other states have adopted the Dade County impact requirements opting that new window construction, meet Dade County standards. Many of the islands in the Caribbean also require these specifications in their impact resistant windows.
Initially, impact standards were so severs that windows meeting these standards were either too expensive or had other negative properties that made implementation impractical.
Currently, Dade County requirements are described in A.S.T.M. 1886-97, A.S.T.M. 1996, A.S.T.M., E-1300 and protocol PA 201,202 and 203.
Description of the Test:
Large Missile Impact
                1. The subject window with frame is placed in a confining apparatus. Thickness of the window can vary but a maximum thickness of 9/16″ is desirable. Area of the glass structure varies according to the application. The framing system is as important as the impact resistance of the glass laminate.        2. An air compressor cannon fires two eight foot 2′ by 4′ wood beams at the center and corner of the glass laminate. Impact occurs at the edge of the wood beam. An additional wood beam is fired at the frame. Distance from the cannon can vary but at impact, the beam must be traveling at 34 miles per hour. If no penetration on impact occurs with the glass and the seal remains in tact on the frame, the impact part of the test in considered a pass. The glass can break both in the front and back with spall and still be considered a pass. To insure the seal on the frame is in tact, a high pressure stream of water is sprayed on the seal for 2–5 minutes. No water penetration can occur. Qualifications are conducted individually and certified on various glass area sizes.        
Although not required, glass laminate systems can be subject to original impact speed of 55 miles per hour with the above procedure. The later speed was considered too severe for the early hurricane resistant windows and was reduced to 34 miles per hour. The object of this testing is strictly as a sales tool.                3. The second part of the test involves pressure and vacuum testing. Diaphragms are placed over the impacted glass and subjected to pressure and vacuum cycling. In order to pass the structure must be capable of holding vacuum and pressure after impact. The severity of the cycling is dependent on the application. High rise buildings require maximum resistance to vacuum and pressure.        4. An optional test involves placing a metal bulb around the impacted area on the reverse side of the hit. Contact points are held in place and increasing pressure is applied and measured until rupture occurs. This test measures the strength of the structure after impact.Small Missile Impact        1. The subject window is placed in a framing system similar to large missile impact.        2. The air compressor cannon is loaded with ten 2 grams each, round steel balls. The cannon fire these steel balls 85 miles per hour in a spray pattern at the glass laminate system. Three shots are required. No penetration or loss of seal can occur in order to pass this test.        3. All requirements of the large missile impact test apply.Notes        1. In many cases, the large missile impact and small missile impact tests are performed on the same glass lamination systems.        2. Glass laminates that pass large missile impact will usually pass small missile impact but not necessarily visa versa.        3. Systems that pass large missile impact testing are used in areas where the possibility of impact by debris, e.g. the first five floors of a high rise or low lying condos, is high.        4. Systems that pass small missile impact testing are used in areas where debris impacts are minimal, e.g. high rise buildings and windows that are protected from direct impacts.        5. In all cases, Hurricane resistant windows must meet A.S.T.M. E1300 wind loading requirements. Except for heavy float glass, these windows must use either heat strengthened or tempered glass.        
6. Requirements for Hurricane Resistant impact test have been varying from county to county and from state to state. In addition, impact codes for blast resistant glass and Tornado resistant glass are in the developmental stage. Application of the invention can be applied to these areas.
Cycling Test
After impact tests have been performed with no penetration of loss of seal, the structure is subjected to vacuum and pressure cycling with plastic diagrams on both sides of the glass and frame. No loss of vacuum or pressure can occur during the cycling. Degree of pressure, vacuum and number of cycles vary with requirements of the application.
For further details, see U.S. Pat. No. 6,450,041 (2002) and U.S. Pat. No. 5,505,091 (1996).
Prior to certification of impact resistance, the inter layer or plastic structure must be certified. Five test are performed on the inter layer or plastic structure for certification.                1. Accelerated UV exposure per 4500 hours, A.S.T.M. G26/G155        2. Textile Test, A.S.T.M. D638        3. Self Ignition, A.S.T.M. D1929        4. Rate of Burning, A.S.T.M. D635        5. Smoke Density, A.S.T.M. D2843        
The certification of the inter layer or plastic sheet takes 6 months. The impact test can be performed as soon as samples are prepared and ready to be evaluated.
For additional information see above mentioned patents.
The above mentioned patents, which are relied upon and incorporated by reference herein, provide additional information.